Thread: need help with theftlock in '08 GXP

I bought this '08 GXP a year ago for my wife, the radio reception is pretty poor. after searching a bit, I found an after market device from "SoundGate" that adds 2 aux inputs in place of the XM bands. SoundGate model #SDSGM2. I am not familiar with these types of radios, My personal truck is a '71 Cheyenne. the Manual says the theftlock arms when the ignition is turned off but does not says how to disarm so i can disconnect the battery. I thought about disconnecting the battery with the ignition key on acc, but else ware in the manual it indicates this wound trigger a backup battery on the onstar system, which would stay on till dead. Can someone help me with the procedure to disconnect the battery safely, And does anyone have thoughts on this SoundGate device, Thanks in advance

Ray

Is it a grand prix GXP? Our cars dont have the theftlock that disables when we take out our battery since the radio and sattelite reciever match the stored vin number to that of the BCM Body Computer to recognize if they couold be stolen or not. So you can unhook the battery as many times as you like.

Even though the manual states theres a backup battery for the onstar...if it is a grand prix I really doubt it has one. They make the manuals very generic and ive seen a few errors throughout them, I know the impala's have them and some other vehicles. If it does it looks like a little black box with two wires almost next to the onstar module( which on the grand prix is a silver module just behind the climnate control) you can see it by looking up under neath the center of the dash from the floor.

I also just looked at the schematic for 08 gxp onstar and confirmed there is no backup battery.

On the soundgate device I never had experience with them but possibly someone else could comment on them,

Thank you michaelbm, yes it is a Grand Prix, my head is still stuck in pre 1972 cars and trucks. and not up to speed with all the new models or technologies. I take it you have the same car, have you tried disconnecting your battery? the manual is confusing. I have spent hours searching google for a solution and have come across your explanation so i just want to verify. We have the stock CD/radio with monsoon sound system (that what it say when i turn on the radio and imprinted on the speakers) The radio reception sucks, so aux input would be a god send for her. She loves this car, me not so much since i'm a big person. although when i do drive it i love to put my foot down to the floor! that is one fast V8, thanks, again

Yup I have the same car except not a gxp and 06 so it has the 3800 SC engine instead, Ive disconnected the battery many times, some of the major electrical mods Ive done to it was converting it to dual climate, factory navigation, xm radio and installing heads up display.

I got a program that has all the service info, procedures and schematics for all the systems.

Mine also has the monsoon system in it as well with the factory amp in the trunk and center dash speaker.

When you disconnect the battery just disconnect the negative first(prevents accidents from happening) and youll be good, if your observent you might notice different driving behavior for a first trip or so just while the computer is relearning the sensor data and stuff like that.

If you need anything else let us know or pm me, I know the whole car inside out and where everything is.

thanks again michaelbm, you are a saint. That puts my mind at ease, I also thought about putting a factory navigation in when I saw used ones on the web, I'm guessing you probably had to have the VIN # changed in the unit? I couldn't find a used one locally though. I think though, adding two AUX inputs and her using her android phone for google NAV and internet/MP3 was a good trade off here is the AUX unit I bought Amazon.com: SOUNDGATE SDSGM2 Auxiliary Interface for 2003-2005 GM With Factory XM Satellite Radio: Electronics I have two other question for you this device I bought and have in hand, has a wiring harness with a male and female factory connectors that plugs in between the 12 pin connector at the back of the radio, can you possibly share what the "pinout" of this connector goes to? I have found information on the 24 pin connector but nothing on this 12 pin connector. Second question is where to get this program you mentioned on servicing this car. Thanks in advance, Ray

I noticed the radio in my 97 GTP has theftlock printed on the front.

Can I swap out the battery without it locking up ?

Just bought car and not sure of history of battery.

thanks